Header repetition in packet-based OFDM systems

ABSTRACT

An OFDM communication system is described that allows different values of D in a single domain where nodes are operating in different portions of frequency bands. For the power-line medium, G.9960 has defined two overlapped baseband bandplans, 50 MHz-PB and 100 MHz-PB. In this exemplary scenario, the level of frequency diversity is different depending on the bandplan, hence providing different header decodibility if D is fixed to 1. If D is fixed to 2, then it increases reliability for the narrowband devices, but may also unnecessarily increase overhead for the wide-band devices. An exemplary aspect is therefore directed to techniques to accommodate different repetitions schemes (D=1, . . . , D MAX  and H=1, . . . , H MAX ) in a single domain, and still allow devices to communicate with one another where D MAX  and H MAX  can be larger than 2.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.17/136,801, filed Dec. 29, 2020, which is a continuation of U.S. patentapplication Ser. No. 16/780,589, filed Feb. 3, 2020, now U.S. Pat. No.10,917,272, which is a continuation of U.S. patent application Ser. No.16/394,490, filed Apr. 25, 2019, now U.S. Pat. No. 10,554,459, which isa continuation of U.S. patent application Ser. No. 16/125,206, filedSep. 7, 2018, now U.S. Pat. No. 10,291,449, which is a continuation ofU.S. patent application Ser. No. 15/958,519, filed Apr. 20, 2018, nowU.S. Pat. No. 10,079,707, which is a continuation of U.S. patentapplication Ser. No. 15/476,284, filed Mar. 31, 2017, now U.S. Pat. No.9,973,361, which is a continuation of U.S. patent application Ser. No.15/350,418, filed Nov. 14, 2016 now U.S. Pat. No. 9,614,566, which is acontinuation of U.S. patent Ser. No. 13/376,856, filed Feb. 8, 2012, nowU.S. Pat. No. 9,584,262, which is a national stage application under 35U.S.C. 371 of PCT Application No. PCT/US2010/046088 having aninternational filing date of Aug. 20, 2010, which designated the UnitedStates, which PCT application claims the benefit of and priority under35 U.S.C. § 119(e) to U.S. Patent Application No. 61/235,909, filed Aug.21, 2009, entitled “Header Repetition Scheme in Packet-Based OFDMSystems,” each of which are incorporated herein by reference in theirentirety.

FIELD

An exemplary aspect of this invention relates to communications systems.More specifically, exemplary methods, systems, means, protocols andcomputer-readable storage media, are directed toward header repetitionin a communications environment.

BACKGROUND

Conventional multi-user communications system use frame-based (orpacket-based) transmission to communication between two or more usersover a shared channel based on Orthogonal Frequency DivisionMultiplexing (OFDM)—(OFDM is also sometimes referred to as multicarriermodulation.) A packet is usually formed by a preamble, header, andpayload, and transmitted using time-sharing or contention-based mediaaccess methods. An example of such a system includes IEEE 802.11(Wireless LAN), IEEE 802.16 (WiMAX), and ITU G.9960 (G.hn). Thesesystems use OFDM transmission, which is also sometimes referred to asDiscrete Multi-Tone (DMT) which divides the transmission frequency bandinto multiple subcarriers (also referred to as tones or sub-channels),with each sub-carrier individually modulating a bit or a collection ofbits.

The header contains important control information for the receiver todecode the payload properly, and also provides information about thepacket length for virtual carrier sensing. Hence, it is essential todecode the header reliably. In G.9960, which is incorporated herein byreference in its entirety, and should be familiar to those skilled inthe art, the header containing PHY_(H) bits (header information block)is carried over one or two OFDM symbols (D=1 or 2), and within eachsymbol, multiple header information blocks are repeated over the entirefrequency band. (See Editor for G.9960, “ITU-T Recommendation G.9960:Next generation wire-line based home networkingtransceivers—Foundation,” ITU-T SG15/04, January 2009) The default valueof D is 1, but expanding it to 2 in some cases is under discussion. See,for example, “G.hn: PHY-Frame Header Extension,” ITU Temporary DocumentITU-T SG-15/Q4 09CC-046, August 2009, and ITU Temporary Document ITU-TSG15/Q4 09XC-100 entitled “G.hn: Using Two Symbols for the Header of PHYFrame on Coax,” July, 2009, filed in the priority application andincorporated herein by reference in their entirety.

The possibility of carrying more than PHY_(H) bits in the header (H=1 or2) is also under discussion as disclosed in the “G.hn: PHY-Frame HeaderExtension” article and in “G.hn: Extended PHY Frame Header,” ITU-T5G15/04 09XC-119, July 2009, filed in the priority application andincorporated herein by reference in their entirety.

SUMMARY

One exemplary technique discussed herein is allowing different values ofD in a single domain where nodes are operating in different portions offrequency bands. For the power-line medium, G.9960 has defined twooverlapped baseband bandplans, 50 MHz-PB and 100 MHz-PB. The possibilityof having narrower bandplans such as 25 MHz-PB and 12.5 MHz-PB are underdiscussion in order to support, for example, SmartGrid applications.

In this exemplary scenario, the level of frequency diversity isdifferent depending on the bandplan, hence providing different headerdecodability if D is fixed to 1. If D is fixed to 2, then it increasesreliability for the narrowband devices, but may also unnecessarilyincrease overhead for the wide-band devices.

An exemplary aspect is therefore directed to techniques to accommodatedifferent repetitions schemes (D=1, . . . , D_(MAX) and H=1, . . . ,H_(MAX)) in a single domain, and still allow devices to communicate withone another. D_(MAX) and H_(MAX) can be 2 or larger than 2.

As illustrated in FIG. 1, various header repetition schemes areillustrated where D, H=1 or 2. In FIG. 1, the second instance of a blockwith the same label is a copy of the prior block. The modulation of thecopied block may not be exactly the same as the original version. Forexample, the label “Header Ext” emphasizes the fact that it may containdifferent header information than the “Header.” The payload after theheader may be omitted in some cases (e.g., ACK, RTS/CTS, etc.).

The repetition scheme expands similarly with larger values of D_(MAX)and H_(MAX). An exemplary aspect focuses on dealing with differentvalues of D, with different values of H capable of being supported in astraightforward way as discussed in the paper G.hn: PHY-Frame HeaderExtension.

On exemplary aspect is directed toward receiver detection of D withvariable repetition. More specifically, in accordance with thisexemplary embodiment, the transmitter selects (or determines), the atleast one D value. The selection may be at its own discretion, or may bebased on information communicated between one or more receivers, orbased on instruction(s) from one or more other receivers and/or a domainmaster. Selection may depend on the number of available sub-carriers (orthe bandwidth) of the bandplan the transmitter operates on and/or thereceiver(s) operates on. In accordance with this exemplary embodiment, areceiving node in the domain should be able to decode packets sent bythe transmitter without knowing D a priori (i.e. prior to decoding thepacket header).

Another exemplary aspect is for a transmitter to carry, insert orotherwise communicate the value of D in the header so that all nodesknow how many OFDM symbols are carrying header information. Thereceiver(s) starts processing the header by decoding one OFDM headersymbol. If the receiver decodes it successfully, then the receiver knowshow many more OFDM symbols (D−1) are carrying header information for agiven frame. If the receiver fails to obtain the header information fromthe OFDM header symbol (i.e., the header decoding fails), then thereceiver can try to decode two OFDM header symbols, and so on. Thedecoding of each additional OFDM header symbol provides additionaldiversity thereby increasing the likelihood of decoding the headerinformation correctly.

Another exemplary aspect is directed to a fixed repetition scheme perdomain. More specifically, a domain master can select (or determine) oneor more fixed D values for at least one node in the domain. For example,the domain master may select one fixed value for all nodes in a domain.Selection may depend on the number of available sub-carriers (or thebandwidth) of the bandplans that the domain members operate on. Thedomain master may change the value of D dynamically. A node in thedomain first needs to determine the D that the domain master has set (orselected/determined).

On exemplary aspect is for the domain master to carry, insert orotherwise communicate the selected value of D in the header of the MAPframe while also using this D value for the transmission of the MAPheader as described above. In this case, a node will be able todetermine the value of D using the methods described above. After thisvalue is determined by a node, the node can use this value until it ischanged or updated by, for example, a domain master, anothertransceiver, etc.

Another exemplary aspect is for the domain master to carry, insert orotherwise communicate the selected value of D in the MAP while using afixed D for the header of the MAP frame (e.g., pre-defined per medium orD_(MAX)). The D value in the MAP will be used for non-MAPframes/packets. In this case, a node in the domain may not need multiplelevels of header decode process as described in above. Also in thisexemplary method, the MAP may be sent with a different D value than theD value used for other (non-MAP) frames/packets.

Another exemplary aspect is directed toward a fixed repetition schemeper TXOP.

More specifically, in addition, or alternatively, the domain master mayselect (or determine) a D value per TXOP. This selection may be at itsown discretion, or based on information communicated between one or moretransceivers or receivers, or based on instruction from one or moretransceivers or receivers. Selection may depend on the number ofavailable sub-carriers (and/or the bandwidth) of the bandplan thetransmitter/transceiver operates on and/or the receiver(s) operates on.

An exemplary technique is to include D in the TXOP descriptortransmitted in the MAP so that all nodes know in advance what value of Dis used for that TXOP. The TXOP descriptor is the part of the MAPmessage which can be communicated via the MAP frame as discussed above.

Any of the above aspects and further aspects may be located in a networkmanagement system or network operation device that is located inside oroutside the network and/or the transceiver(s). The network operation ormanagement device that is located inside or outside the network may bemanaged and/or operated by a user, consumer, service provider or powerutility provider, a governmental entity, or the like.

BRIEF DESCRIPTION ON THE DRAWINGS

The exemplary embodiments of the invention will be described in detail,with reference to the following figures, wherein:

FIG. 1 illustrates exemplary header repetition schemes;

FIG. 2 illustrates an exemplary transceiver;

FIG. 3 illustrates an exemplary communications environment;

FIG. 4 is a flowchart outlining an exemplary method of a headerrepetition scheme;

FIG. 5 is a flowchart outlining another exemplary method for a headerrepetition scheme;

FIG. 6 is a flowchart outlining yet another exemplary method for aheader repetition scheme;

FIG. 7 is a flowchart outlining another exemplary method for a headerrepetition scheme; and

FIG. 8 is a flowchart outlining another method of an exemplary headerrepetition scheme.

DETAILED DESCRIPTION

The exemplary embodiments of this invention will be described inrelation to communications systems, as well as protocols, techniques andmethods for header repetition, such as in a DSL or multimodemulticarrier communications environment, a home network or an accessnetwork, or in general any communications network operating using anycommunications protocol(s). Examples of such home or access networksinclude home powerline networks, access powerline networks, home coaxialcable network, access coaxial cable network, wireless home networks,wireless corporate networks, home telephone networks and accesstelephone networks. However, it should be appreciated that in general,the systems, methods, and techniques of this invention will work equallywell for other types of communications environments, networks, and/orprotocols.

The exemplary systems and methods of this invention will also bedescribed in relation to wired or wireless modems and/or a softwareand/or a hardware testing module, a telecommunications test device, orthe like, such as a DSL modem, an ADSL modem, and xDSL modem, a VDSLmodem, a line card, a G.hn transceiver, a MOCA transceiver, a Homeplug®transceiver, a power line modem, a wired or wireless modem, testequipment, a multicarrier transceiver, a wireless wide/local areanetwork system, a satellite communications system, a network-basedcommunications systems, such as an IP, Ethernet or ATM system, a modemequipped with diagnostic capabilities, or the like, or a separateprogrammed general purpose computer having a communications device thatis capable of operating in conjunction with any one or more of thefollowing communications protocols: MOCA, Homeplug, IEEE 802.11, IEEE802.3, IEEE 802.16 (WiMAX), and ITU G.9960 (G.hn), or the like. However,to avoid unnecessarily obscuring the present invention, the followingdescription omits well-known structures, operations and devices that maybe shown in block diagram form or are otherwise summarized or known.

For purposes of explanation, numerous details are set forth in order toprovide a thorough understanding of the present invention. It should beappreciated however that the present invention may be practiced in avariety of ways beyond the specific details set forth herein.Furthermore, while the exemplary embodiments illustrated herein showvarious components of this system collocated, it is to be appreciatedthat the various components of the system can be located at distantportions of a distributed network, such as a communications network,node, within a Domain Master, and/or the internet, or within a dedicatedsecured, unsecured, and/or encrypted system and/or within a networkoperation or management device that is located inside or outside thenetwork. As an example, a Domain Master can also be used to refer to anydevice, system or module that manages and/or configures any one or moreaspects of the network or communications environment.

Thus, it should be appreciated that the components of the system can becombined into one or more devices, or split between devices, such as amodem, a station, a Domain Master, a network operation or managementdevice, a node or collocated on a particular node of a distributednetwork, such as a communications network. As will be appreciated fromthe following description, and for reasons of computational efficiency,the components of the system can be arranged at any location within adistributed network without affecting the operation thereof. Forexample, the various components can be located in a Domain Master, anode, a domain management device, such as a MIB, a network operation ormanagement device, or some combination thereof. Similarly, one or moreof the functional portions of the system could be distributed between amodem and an associated computing device/system, and/or in a dedicatedtest and/or measurement device.

Furthermore, it should be appreciated that the various links 5,including the communications channel(s) connecting the elements can bewired or wireless links or any combination thereof, or any other knownor later developed element(s) capable of supplying and/or communicatingdata to and from the connected elements. The term module as used hereincan refer to any known or later developed hardware, software, firmware,or combination thereof, that is capable of performing the functionalityassociated with that element. The terms determine, calculate, andcompute and variations thereof, as used herein are used interchangeableand include any type of methodology, process, technique, mathematicaloperational or protocol. The terms transceiver and modem are also usedinterchangeably herein. The terms transmitting modem and transmittingtransceiver as well as receiving modem and receiving transceiver arealso used interchangeably herein.

The term management interface is related to any type of interfacebetween a management entity and/or technician and/or user and atransceiver, such as, a CO-MIB or CPE-MIB as described, for example, inITU standard G.997.1, which is incorporated herein by reference in itsentirety.

Moreover, while some of the exemplary embodiments described herein aredirected toward a transmitter portion of a transceiver performingcertain functions, this disclosure is intended to include correspondingreceiver-side functionality in both the same transceiver and/or anothertransceiver, and vice versa.

FIG. 1 illustrates four different header configurations where D, H, =1or 2. Even more specifically, in the first example, H=1 and D=1 with apreamble followed by a header followed by a payload. In a second exampleH=1 and D=2, with the preamble followed by header 2 that is repeated asheader 4, which is followed by the payload. As discussed, the repeatedheader can be repeated in full or in part. In the third example, H=2 andD=1, such that the preamble is followed by a header which is followed byan extended header and the payload. In the fourth example, H=2 and D=2such that header 6 is repeated as header 8, and the extended header 3 isrepeated as extended header 5, which is followed by the payload. Asdiscussed, the repeated portions may be exact duplicates.

As a more specific example, consider the header configuration in thefifth example. In the fifth example, H is again equal to 2 and D isequal to 2 such that header 11 is repeated as header 12, and theextended header 13 is repeated as extended header 14, which is followedby the payload. For this example, the “Header” is limited to a certainnumber of bits (here arbitrarily illustrated as 10 bits), however, forthis example, there are 15 bits of information that need to be includedin the header. Thus, 10 bits are included in the “Header” and theremaining 5 bits are included in the “Header Ext.” As will beappreciated, the number of information bits to be included in theheader, the number of bits the header is capable of carrying and thenumber of bits the header extended is capable of carrying can be anyvalue(s). The 10 bits in “Header” 11 are repeated in “Header” 12 and the5 bits in “Header Ext” 13 and repeated in “Header Ext” 14.

FIG. 2 illustrates an exemplary transceiver or Domain Master 200. Inaddition to well known componentry, the transceiver or Domain Master 200includes (for a Domain Master) a MAP determination module 210 and (for atransceiver) a MAP processing or relaying module 210, a header assemblymodule 220, modulation module 230, demodulation module 240, transmitter250, encoding module 260, decoding module 270, receiver 280, andcontroller/processor 290. In general, a Domain Master generallydetermines a MAP frame for transmission to one or more othertransceivers while a transceiver is capable of one or more of receivingand/or relaying the received MAP frame to one or more othertransceivers. For ease of discussion, in the following description, thedetermining and transmitting of a MAP frame will be performed by aDomain Master-type of transceiver and the receiving and/or relaying of aMAP frame will be performed by a non-domain master type of transceiver.However, the description also allows and enables any transceiver (Domainmaster or non-domain master) to determine, transmit, receiver and/orrelay MAP messages.

In operation, the transceiver or Domain Master 200, cooperating with theMAP determination module or MAP processing or relaying module 210,transmitter 250, and controller/processor 290 transmits a MAP frame thatincludes a TXOP descriptor. As discussed, this TXOP descriptor containsa bit field that indicates a value for an integer (D) where the integerD indicates a number of header OFDM symbols that carry header bits.Next, the transceiver or Domain Master 200, cooperating with the headerassembly module 220 and transmitter 250 prepares to transmit a secondframe having a plurality of header bits using the D header OFDM symbols.Each OFDM symbol carries the plurality of header bits. Then, incooperation with the modulation module 230, the transceiver or DomainMaster 200 modulates the header bit onto the D OFDM symbols. Asdiscussed, this modulation of the header bits onto the D OFDM symbolscan occur where the header bits are modulated onto the D OFDM symbols inthe same order or can occur where the header bits are modulated onto theD OFDM symbols in a different order. In addition, the encoding module260 may encode the value of D into a bit field on the header of thesecond frame. The second frame is then transmitted over thecommunications channel.

As discussed, the value of D can be updated based, for example, oninformation received from another transceiver, on information receivedfrom a domain master, can be initiated by the controller/processor 290,or can in general be initiated and/or requested by any other device,wherein the value of D that is updated is different than the previousvalue of D. With the updated value of D, the above-described steps canbe repeated utilizing this updated value of D.

In accordance with another exemplary operational embodiment, thetransceiver or Domain Master 200 transmits a MAP frame that includes theTXOP descriptor and then receives a second frame that has a plurality ofheader bits that use the D header OFDM symbols. This is followed by thedemodulation module 240 demodulating the header bits from the D OFDMsymbols that were received. Additionally, the decoding module 270 maydecode the value of D from a bit field in the header of the receivedsecond frame. As with the previous embodiment, the value of D can beupdated with the above steps being repeated.

In accordance with yet another exemplary operational embodiment, thetransceiver 200 first receives the MAP frame that includes the TXOPdescriptor with the cooperation of the receiver 280. The transceiver200, with the cooperation of the header assembly module 220, andtransmitter 250, transmits a second frame having a plurality of headerbits using the D header OFDM symbols. As with the previous embodiments,the header bits are modulated onto the D OFDM symbols either the same orin a different order, and the value of D may be encoded in a bit fieldin the header of the second frame. Again, this can be followed by anupdated value of D with the above steps being repeated.

In yet another exemplary operational embodiment, the transceiver 200receives a MAP frame that includes the TXOP descriptor, which isfollowed by the receipt of a second frame that has a plurality of headerbits that used the D header OFDM symbols. As with one of the aboveexemplary embodiments, this is done with the cooperation of the receiver280, the demodulation module 240 and decoding module 270. Upon receipt,the header bits from the D OFDM symbols can be demodulated and the valueof D from a bit field in the header of the second frame may be decoded.

FIG. 3 illustrates an exemplary communications environment that includesa first transceiver or domain master 310 and a second transceiver 320.While not illustrated in FIG. 3, there could be one or more additionaltransceivers that act as relays to pass the various informationalmessages and data exchanged between the transceivers to therebyfacilitate communication between the first transceiver or domain master310 and the second transceiver 320.

In operation, the transceiver and/or domain master 310, cooperating withthe MAP determination module or MAP processing or relaying module 210,transmitter 250, and controller/processor 290 transmits a MAP frame thatincludes a TXOP descriptor over the communications channel to the secondtransceiver 320. As discussed, this TXOP descriptor contains a bit fieldthat indicates a value for an integer (D) where the integer D indicatesa number of header OFDM symbols that carry header bits. Next, thetransceiver/domain master 310, cooperating with the header assemblymodule 220 and transmitter 250 prepares to transmit a second frame totransceiver 320 having a plurality of header bits using the D headerOFDM symbols. Each OFDM symbol carries the plurality of header bits.Then, in cooperation with the modulation module 230, thetransceiver/domain master 310 modulates the header bit onto the D OFDMsymbols. As discussed, this modulation of the header bits onto the DOFDM symbols can occur where the header bits are modulated onto the DOFDM symbols in the same order or can occur where the header bits aremodulated onto the D OFDM symbols in a different order. In addition, theencoding module 260 may encode the value of D into a bit field on theheader of the second frame. The second frame is then transmitted overthe communications channel to the second transceiver 320.

As discussed, the value of D can be updated based, for example, oninformation received from another transceiver, on information receivedfrom a domain master, can be initiated by the controller/processor 290,or can in general be initiated and/or requested by any other device,wherein the value of D that is updated is different than a previousvalue of D. With the updated value of D, the above-described steps canbe repeated utilizing this updated value of D.

In accordance with another exemplary operational embodiment, thetransceiver/domain master 310 transmits a MAP frame that includes theTXOP descriptor to the second transceiver 320 and then receives from thesecond transceiver 320 a second frame that has a plurality of headerbits that use the D header OFDM symbols. This is followed by thetransceiver/domain master's 310 demodulation module 240 demodulating theheader bits from the D OFDM symbols that were received. Additionally,the decoding module 270 of the transceiver/domain master 310 decodes thevalue of D from the bit in the header of the received second frame. Aswith the previous embodiment, the value of D can be updated with theabove steps being repeated.

In accordance with yet another exemplary operational embodiment, thetransceiver/domain master 310 first receives the MAP frame that includesthe TXOP descriptor from the second transceiver 320 with the cooperationof the receiver 280 in the transceiver/domain master 310. Thetransceiver/domain master 310, with the cooperation of the headerassembly module 220, and transmitter 250, transmits a second framehaving a plurality of header bits using the D header OFDM symbols to thesecond transceiver 320. As with the previous embodiments, the headerbits are modulated onto the D OFDM symbols either the same or in adifferent order, and the value of D encoded in a bit field in the headerof the second frame. Again, this can be followed by an updated value ofD with the above steps being repeated.

In yet another exemplary operational embodiment, the transceiver/domainmaster 310 receives a MAP frame from the transceiver 320 that includesthe TXOP descriptor, which is followed by the receipt of a second framethat has a plurality of header bits that used the D header OFDM symbols.As with one of the above embodiments, this is done with the cooperationof the receiver 280, the demodulation module 240 and decoding module270. Upon receipt, the header bits from the D OFDM symbols can bedemodulated and the value of D from a bit field in the header of thesecond frame decoded. Again, this can be followed by an updated value ofD with the above steps being repeated.

FIG. 4 illustrates an exemplary method of packet transmission. Inparticular, control begins in step S400 and continues to step S410. Instep S410, a MAP frame is transmitted, with the MAP frame including aTXOP descriptor. As discussed, the TXOP descriptor can contain a bitfield that indicates a value for an integer (D) wherein the integer Dindicates a number of header OFDM symbols that carry header bits. TheTXOP descriptor could contain multiple bit fields that indicate morethan a value for the integer D as well. Next, in step S420, a secondframe is prepared for transmission, the second frame having a pluralityof header bits using D header OFDM symbols. Then, in step S430, thevalue of D is encoded into a bit field in the header of the secondframe. Control then continues to step S440.

In step S440, the header bits are modulated onto the D OFDM symbols ineither the same order or in a different order. Then, in step S450, thesecond frame is transmitted with control continuing to step S460.

In step S460, the value of D can optionally be updated with stepsS410-S450 being repeated. Control then continues to step S470 where thecontrol sequence ends.

FIG. 5 illustrates an exemplary method of packet reception. Inparticular, control begins in step S500 and continues to step S510. Instep S510, a MAP frame is received, with the MAP frame including a TXOPdescriptor. As discussed, the TXOP descriptor contains a bit field thatindicates a value for an integer (D) wherein the integer D indicates anumber of header OFDM symbols that carry header bits. Next, in stepS520, a second frame is received, the second frame having a plurality ofheader bits that used the D header OFDM symbols. Then, in step S530, theheader bits are demodulated from the D OFDM symbols in the same order orin a different order. Control then continues to step S540.

In step S540, the value of D is decoded from a bit field in the headerof the second frame. Then, in step S550, the value of D can optionallybe updated with steps S510-S540 being repeated. Control then continuesto step S560 where the control sequence ends.

FIG. 6 illustrates an exemplary method of packet communication. Inparticular, control begins in step S600 in a first transceiver or DomainMaster and continues to step S610. In step S610, a MAP frame istransmitted to a second transceiver, with the MAP frame including a TXOPdescriptor. For the second transceiver, control begins in step S602 andcontinues to step S604 where the MAP frame including the TXOP descriptoris received.

Next, in step S620, a second frame is prepared for transmission andtransmitted to the second transceiver, the second frame having aplurality of header bits using D header OFDM symbols. As discussed theheader bits are modulated onto the D OFDM symbols with the TXOPdescriptor containing a bit field that indicates a value for a integer(D) wherein the integer D indicates a number of header OFDM symbols thatcarry header bits. The TXOP descriptor could contain multiple bit fieldsthat indicate more than a value for the integer D as well. Additionally,the header bits can be modulated onto the D OFDM symbols in the sameorder or in a different order and the value of D encoded into a bitfield in the header of the second frame. Control for the firsttransceiver then continues to step S630 where the control sequence ends.

In step S606, the second frame is received, the second frame having theplurality of header bits that used the D header OFDM symbols. Then, instep S608, the header bits are demodulated from the D OFDM symbols inthe same order or in a different order with control continuing to stepS612.

In step S612, the value of D is decoded from the bit field in the headerof the second frame. Then, in step S612, the value of D can optionallybe updated with steps S610, S620 and S604-S612 being repeated. Controlthen continues to step S616 where the control sequence ends.

FIG. 7 illustrates an exemplary method of packet communication. Inparticular, control begins in step S700 in a first transceiver or DomainMaster and continues to step S710. In step S710, a MAP frame istransmitted to a second transceiver, with the MAP frame including a TXOPdescriptor. Control then continues to step S720 where the controlsequence ends.

For the second transceiver, control begins in step S702 and continues tostep S704 where after receipt of the MAP frame that includes the TXOPdescriptor, a second frame is prepared by the second transceiver fortransmission, the second frame having a plurality of header bits using Dheader OFDM symbols. Then, in step S706, the value of D is encoded intoa bit field in the header of the second frame with control continuing tostep S708.

In step S708, the header bits are modulated onto the D OFDM symbols inthe same order or in a different order. Then, in step S712, the secondframe is transmitted with control continuing to step S714.

In step S714, the value of D can optionally be updated with steps S710and S704-S712 being repeated. Control then continues to step S716 wherethe control sequence ends.

FIG. 8 illustrates another exemplary method of packet communication. Inparticular, control begins in step S800 in a first transceiver or DomainMaster and continues to step S810. In step S810, a MAP frame istransmitted to a second transceiver, optionally being relayed by one ormore other transceivers, with the MAP frame including a TXOP descriptor.Control then continues to step S820 where the control sequence ends. Therelaying of one or more of the MAP frame and second frame as discussedherein is not limited to this specific embodiment, but could also occurin any of the other embodiments disclosed herein.

For the second transceiver, control begins in step S802 and continues tostep S804 where the MAP frame that includes the TXOP descriptor isreceived. Next, in step S806 a second frame is prepared by the secondtransceiver for transmission, the second frame having a plurality ofheader bits using D header OFDM symbols. Then, in step S808, the valueof D is encoded into a bit field in the header of the second frame withcontrol continuing to step S812.

In step S812, the header bits are modulated onto the D OFDM symbols inthe same order or in a different order. Then, in step S814, the secondframe is transmitted with control continuing to step S816.

In step S816, the value of D can optionally be updated with steps S810and S804-S814 being repeated using the updated value of D. Control thencontinues to step S818 where the control sequence ends.

As used herein the terms network and domain have the same meaning andare used interchangeably. Also, the terms receiver, receiving node andreceiving transceiver have the same meaning and are usedinterchangeably. Similarly, the terms transmitter, transmitting node andtransmitting transceiver have the same meaning and are usedinterchangeably. The terms transceiver and modem also have the samemeaning and are used interchangeably. While the term home network hasbeen used in this description, the description is not limited to homenetworks but in fact applies also to any network, such as enterprisenetworks, business networks, or any network with a plurality ofconnected nodes. The terms transceiver, node and modem have the samemeaning and are used interchangeably in the description. The term frameand packet have the same meaning and are used interchangeably in thedescription. The term header and PHY-frame header have the same meaningand are used interchangeably in the description.

The terms network and home network have the same meaning and are usedinterchangeably in the description. While the term Home network has beenused in this description, the description is not limited to homenetworks but in fact applies also to any network, such as enterprisenetworks, business networks, or any network with a plurality ofconnected nodes.

While the above-described methods and systems can be described withrespect to a port (or endpoint) in a network, they can also beimplemented in a dedicated module such as a test or network optimizationmodule. This dedicated module could be plugged into the network and actas a Domain Master or with the cooperation of the Domain Master couldinitiate the various measurement techniques, gather the measurementsfrom the port(s) in the network, analyze the measurements and use themeasured information to detect and diagnose problems in the networkand/or to optimize or improve the performance of a network.

While the above-described flowcharts have been discussed in relation toa particular sequence of events, it should be appreciated that one ormore changes to this sequence can occur without materially effecting theoperation of the embodiments. Additionally, the exact sequence of eventsneed not occur as set forth in the exemplary embodiments. The exemplarytechniques illustrated herein are not limited to the specificallyillustrated embodiments but can also be utilized with the otherexemplary embodiments and each described feature is individually andseparately claimable. Moreover, the steps in the flowcharts areoptional, with some of or all of the steps being performed.

The above-described methods and systems and can be implemented in asoftware module, a software and/or hardware testing module, atelecommunications test device, a DSL modem, an ADSL modem, an xDSLmodem, a VDSL modem, a linecard, a G.hn transceiver, a MOCA transceiver,a Homeplug transceiver, a powerline modem, a wired or wireless modem,test equipment, a multicarrier transceiver, a wired and/or wirelesswide/local area network system, a satellite communication system,network-based communication systems, such as an IP, Ethernet or ATMsystem, a modem equipped with diagnostic capabilities, or the like, oron a separate programmed general purpose computer having acommunications device or in conjunction with any of the followingcommunications protocols: CDSL, ADSL2, ADSL2+, VDSL1, VDSL2, HDSL, DSLLite, IDSL, RADSL, SDSL, UDSL, MOCA, G.hn, Homeplug® or the like.

Additionally, the systems, methods and protocols of this invention canbe implemented on a special purpose computer, a programmedmicroprocessor or microcontroller and peripheral integrated circuitelement(s), an ASIC or other integrated circuit, a digital signalprocessor, a flashable device, a hard-wired electronic or logic circuitsuch as discrete element circuit, a programmable logic device such asPLD, PLA, FPGA, PAL, a modem, a transmitter/receiver, any comparablemeans, or the like. In general, any device (or one or more equivalentmeans) capable of implementing a state machine that is in turn capableof implementing the methodology illustrated herein can be used toimplement the various communication/measurement methods, protocols andtechniques according to this invention.

Furthermore, the disclosed methods may be readily implemented insoftware stored on a non-transitory computer-readable storage mediausing object or object-oriented software development environments thatprovide portable source code that can be used on a variety of computeror workstation platforms. Alternatively, the disclosed system may beimplemented partially or fully in hardware using standard logic circuitsor VLSI design. Whether software or hardware is used to implement thesystems in accordance with this invention is dependent on the speedand/or efficiency requirements of the system, the particular function,and the particular software or hardware systems or microprocessor ormicrocomputer systems being utilized. The communication systems, methodsand protocols illustrated herein can be readily implemented in hardwareand/or software using any known or later developed systems orstructures, devices and/or software by those of ordinary skill in theapplicable art from the functional description provided herein and witha general basic knowledge of the computer and telecommunications arts.

Moreover, the disclosed methods may be readily implemented in softwarethat can be stored on a computer-readable storage medium, executed onprogrammed general-purpose computer with the cooperation of a controllerand memory, a special purpose computer, a microprocessor, or the like.The systems and methods of this invention can be implemented as aprogram embedded on personal computer such as an applet, JAVA® or CGIscript, as a resource residing on a server or computer workstation, as aroutine embedded in a dedicated communication system or systemcomponent, or the like. The system can also be implemented by physicallyincorporating the system and/or method into a software and/or hardwaresystem, such as the hardware and software systems of a test/modemdevice.

While the invention is described in terms of exemplary embodiments, itshould be appreciated that any of the aspects of the invention describedherein in connection with the exemplary embodiments could be separatelyand individually claimed and one or more of the features of the variousembodiments can be combined with one or more features discussed inrelation to one or more other embodiments.

While the exemplary embodiments illustrated herein discuss the variouscomponents collocated, it is to be appreciated that the variouscomponents of the system can be located a distant portions of adistributed network, such as a telecommunications network and/or theInternet or within a dedicated communications network. Thus, it shouldbe appreciated that the components of the system can be combined intoone or more devices or collocated on a particular node of a distributednetwork, such as a telecommunications network. As will be appreciatedfrom the following description, and for reasons of computationalefficiency, the components of the communications network can be arrangedat any location within the distributed network without affecting theoperation of the system.

It is therefore apparent that there has been provided, in accordancewith the present invention, systems and methods for header repetition inOFDM systems. While this invention has been described in conjunctionwith a number of embodiments, it is evident that many alternatives,modifications and variations would be or are apparent to those ofordinary skill in the applicable arts. Accordingly, it is intended toembrace all such alternatives, modifications, equivalents and variationsthat are within the spirit and scope of this invention.

What is claimed is:
 1. A wireless communication device, comprising: amodulator configured to modulate a wireless packet to be transmitted;and a wireless transmitter configured to transmit the wireless packetthrough a communication channel, wherein formats of the wireless packetincludes a first packet format and a second packet format, the firstpacket format comprises a first header field carried by a firstorthogonal frequency division multiplexing (OFDM) symbol, the secondpacket format comprises both the first header field carried by the firstOFDM symbol and a second header field carried by a second OFDM symbolwhich follows the first OFDM symbol, and the second header field is arepetition of the first header field, and wherein the wirelesscommunication device is configured to transmit the wireless packet in aformat determined among the first packet format and the second packetformat.
 2. The wireless communication device of claim 1, wherein whenthe wireless packet is transmitted in the first packet format, thewireless communication device transmits the first header field withouttransmitting the second header field which repeats the first headerfield.
 3. The wireless communication device of claim 1, wherein when thewireless packet is transmitted in the second packet format, the wirelesscommunication device transmits both the first header field and thesecond header field which repeats the first header field.
 4. Thewireless communication device of claim 1, wherein the first and secondheader fields contain information for decoding the wireless packet. 5.The wireless communication device of claim 1, wherein the first andsecond header fields contain information related to a length of thewireless packet.
 6. A wireless communication method, comprising:modulating a wireless packet to be transmitted; and transmitting thewireless packet through a communication channel, wherein formats of thewireless packet includes a first packet format and a second packetformat, the first packet format comprises a first header field carriedby a first orthogonal frequency division multiplexing (OFDM) symbol, thesecond packet format comprises both the first header field carried bythe first OFDM symbol and a second header field carried by a second OFDMsymbol which follows the first OFDM symbol, and the second header fieldis a repetition of the first header field, and wherein the wirelesspacket is configured to be transmitted in a format determined among thefirst packet format and the second packet format.
 7. The wirelesscommunication method of claim 6, wherein when the wireless packet istransmitted in the first packet format, the wireless packet comprisesthe first header field without comprising the second header field whichrepeats the first header field.
 8. The wireless communication method ofclaim 6, wherein when the wireless packet is transmitted in the secondpacket format, the wireless packet comprises both the first header fieldand the second header field which repeats the first header field.
 9. Thewireless communication method of claim 6, wherein the first and secondheader fields contain information for decoding the wireless packet. 10.The wireless communication method of claim 6, wherein the first andsecond header fields contain information related to a length of thewireless packet.